title: Hemoglobin on phosphonic acid terminated self-assembled monolayers at a gold electrode: immobilization, direct electrochemistry, and electrocatalysis.
abstract: Phosphonic acid (--PO(3)H(2)) terminated self-assembled monolayers (SAMs) on a gold surface were used as a functional interface to immobilize hemoglobin (Hb). In situ surface-enhanced infrared absorption spectroscopy (SEIRAS) measurements show that Hb immobilization is a sluggish process due to formation of multilayer Hb structures on the PO(3)H(2)-terminated SAMs, as revealed by ellipsometry, atomic force microscopy (AFM), and cyclic voltammetry (CV). In the multilayered Hb film, the innermost Hb molecules can directly exchange electrons with the electrode, whereas Hb beyond this layer communicates electronically with the electrode via protein-protein electron exchange. In addition, electrochemical measurements indicate that immobilization of Hb on the PO(3)H(2)-terminated SAMs is not driven by the electrostatic interaction, but likely by hydrogen-bonding interaction. The immobilized Hb molecules show excellent bioelectrocatalytic activity towards hydrogen peroxide, that is, the PO(3)H(2)-terminated SAMs are promising for construction of third-generation biosensors.
authors.affiliation: State Key Laboratory of Coordination Chemistry, Coordination Chemistry Institute, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.forename: Bo
authors.initials: B
authors.lastname: Jin
authors.forename: Li-Rong
authors.initials: LR
authors.lastname: Guo
authors.forename: Xiao-Jing
authors.initials: XJ
authors.lastname: Yang
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Gang
authors.initials: G
authors.lastname: Gu
authors.forename: Li-Min
authors.initials: LM
authors.lastname: Zheng
authors.forename: Xing-Hua
authors.initials: XH
authors.lastname: Xia
mesh_terms: D000327:Adsorption; D002384:Catalysis; D004563:Electrochemistry; D004566:Electrodes; D004583:Electrons; D006046:Gold / Q000737:chemistry*; D006454:Hemoglobins / Q000737:chemistry*; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D008567:Membranes, Artificial; D018625:Microscopy, Atomic Force / Q000379:methods; D063065:Organophosphonates / Q000737:chemistry*; D009994:Osmolar Concentration; D013055:Spectrophotometry, Infrared / Q000379:methods; D013499:Surface Properties
chemical_list: D006454:Hemoglobins; D008567:Membranes, Artificial; D063065:Organophosphonates; D006046:Gold